"""
Copyright 2018 Defense Innovation Unit Experimental
All rights reserved.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
"""

from __future__ import division
class Rectangle(object):
  """Rectangle class."""

  def __init__(self, xmin, ymin, xmax, ymax):
    """Constructs a Rectangle instance."""
    if xmin >= xmax or ymin >= ymax:
      self.xmin_ = None
      self.ymin_ = None
      self.xmax_ = None
      self.ymax_ = None
    else:
      self.xmin_ = xmin
      self.ymin_ = ymin
      self.xmax_ = xmax
      self.ymax_ = ymax
    self.coords = (xmin,ymin,xmax,ymax)

  def __eq__(self, other):
    """== operator overloading."""
    return ((self.xmin_ == other.xmin_) and (self.ymin_ == other.ymin_) and
            (self.xmax_ == other.xmax_) and (self.ymax_ == other.ymax_))

  def __ne__(self, other):
    """!= operator overloading."""
    return not self.__eq__(other)

  def is_empty(self):
    """Determines if the Rectangle instance is valid or not."""
    return ((self.xmin_ is None) or (self.ymin_ is None) or
            (self.xmax_ is None) or (self.ymax_ is None) or
            (self.xmin_ >= self.xmax_) or (self.ymin_ >= self.ymax_))

  def width(self):
    """Returns the width of the Rectangle instance."""
    return self.xmax_ - self.xmin_ 

  def height(self):
    """Returns the height of the Rectangle instance."""
    return self.ymax_ - self.ymin_ 

  def area(self):
    """Returns the area of the Rectangle instance."""
    return self.width() * self.height()

  def intersect(self, other):
    """Returns the intersection of this rectangle with the other rectangle."""

    xmin = max(self.xmin_, other.xmin_)
    ymin = max(self.ymin_, other.ymin_)
    xmax = min(self.xmax_, other.xmax_)
    ymax = min(self.ymax_, other.ymax_)
    return Rectangle(xmin, ymin, xmax, ymax)

  def intersects(self, other):
    """Tests if this rectangle has an intersection with another rectangle."""
    return not (self.is_empty() or other.is_empty() or
                (other.xmax_ <= self.xmin_) or (self.xmax_ <= other.xmin_) or
                (other.ymax_ <= self.ymin_) or (self.ymax_ <= other.ymin_))

  def contains(self, x, y):
    """Tests if a point is inside or on any of the edges of the rectangle."""
    return ((x >= self.xmin_) and (x <= self.xmax_) and
            (y >= self.ymin_) and (y <= self.ymax_))

  def intersect_over_union(self, other):
    """Returns the intersection over union ratio of this and other rectangle."""
    if not self.intersects(other):
      return 0.0

    intersect_rect = self.intersect(other)
    if intersect_rect.is_empty():
      return 0.0

    if self.area() == 0 or other.area() == 0:
      return 0.0

    return intersect_rect.area() / (self.area() + other.area() - intersect_rect.area())
